1. Field of the Invention
The present invention relates to an optical transmission module used in optical fiber communications, and particularly to an optical transmission module capable of improving yield, reducing the costs, and preventing the deterioration of high frequency characteristics.
2. Background Art
An optical transmission module has a modulator integrated light-emitting element for receiving an electric signal and converting it to an optical signal, and a ceramic or semiconductor substrate on which this modulator integrated light-emitting element is mounted. On the surface of the substrate, a first transmission line for transmitting the electric signal, a resistance element used as a termination point, a second transmission line connected to the resistance element, and ground patterns that form coplanar lines through the first and second transmission lines, respectively, are formed. On the top face of the modulator integrated light-emitting element, an electrode pad for modulator driving is formed to supply power to the modulator. The first transmission line of the substrate and the electrode pad of the modulator integrated light-emitting element, and the electrode pad of the modulator integrated light-emitting element and the second transmission line of the substrate are connected by wires, respectively (for example, see Japanese Patent Application Laid-Open No. 2005-38984).